In the digital video signal processing, generally a digital video signal is encoded and compressed for the high-speed transmission in a bandwidth-limited channel. For example, Moving Picture Experts Group (MPEG) is a block-based video compression format.
After being encoded and compressed, the video signal is transmitted through a transmission channel to a decoder, which then decodes and decompresses the video signal. However, an annoying block artifact occurs after the decoder reconstructs the video signal such that one can observe obvious block boundaries since the source video signal is encoded on a block-by-block basis.
FIG. 1 is a block diagram of a conventional deblocking apparatus. In a conventional apparatus, a low-pass filter 11 is used to process an input video signal received by a display apparatus to output a filtered video signal. However, an improper process may result in a blurred image and many image details may be lost. Moreover, a conventional technique needs to know a blocking boundary in advance in order to deblock correctly. However, it is difficult to meet such requirement under certain situations at a receiving end, e.g., at an analog television (ATV).
Therefore, it is desirable to provide a deblocking apparatus and an associated method for deblocking effectively without knowing the blocking boundary in advance.